In recent years, with the increase in traffic, for example, on the Internet or the like, optical transmission devices are expected to achieve increase in data capacity and reduction in size. Line cards housed in an optical transmission device are each equipped with a cage, and multiple optical pluggable modules (hereinafter, referred to simply as “modules”) are mounted in the cage. There are multiple types of modules, such as SFP (Small Form-factor Pluggable) modules, XFP (10G Form-factor Pluggable) modules, and CFP (100G Form-factor Pluggable) modules.
Standard specifications for the structure of a cage mounted with modules and the shape of the modules are defined, for example, in INF-8077i in the case of XFP modules and in CFP-MSA in the case of CFP modules. Therefore, modules compliant with standard specifications can be removably mounted into mounting ports in a cage.
However, there exist a variety of modules depending on support conditions, such as a transmission distance and an internal function. For example, XFP modules range in power consumption from 1 to 6 W depending on specifications. Furthermore, CFP modules range in power consumption from 8 to 32 W depending on specifications. Therefore, an amount of generated heat varies according to power consumptions of modules mounted on a line card housed in an optical transmission device, and thus internal device environmental temperature also varies significantly.
Furthermore, a tolerable standard temperature of internal device environmental temperature is set in the optical transmission device, and the optical transmission device adjusts the environmental temperature to be less than or equal to the standard temperature. Specifically, the optical transmission device is equipped with an air-cooling fan for cooling the inside of the device, and adjusts the internal device environmental temperature by controlling the fan. Incidentally, the flow of air from the fan in the optical transmission device depends on the structure and installation position of a cage regardless of whether a module has been mounted in the cage or whether the module has been activated. An example of related art is described in Japanese Laid-open Patent Publication No. 2006-157305, Japanese Laid-open Patent Publication No. 2010-182786 and Japanese Laid-open Patent Publication No. 2005-18309.
In an optical transmission device, internal device environmental temperature varies according to a power consumption of a mounted module; however, it is difficult to determine whether the internal device environmental temperature is less than or equal to a specified internal device temperature, until the module is actually mounted and activated.